The invention relates to a rotor, and in particular, to a rotor with enhanced mechanical strength to be used in the fan.
In a conventional rotor, the shaft and the case are connected as follows.
FIG. 1 depicts a rotor assembled by insert molding, wherein a shaft 20 is disposed in contact with a joining area 11 of a case 10, and then a connecting material (e.g. plastic or soft metal) 30 is provided between the shaft 20 and the case 10 by insert molding. Thus, the shaft 20 is firmly connected to the case 11.
FIG. 2 depicts another rotor assembled by fitting-and-riveting, wherein a shaft 20 is fitted into a copper cover 40, and then the copper cover 40 and the case 10 are connected by riveting (i.e. the copper cover 40 is passed through an opening 12 of a case 10, and the part of the copper cover 40 projecting from the opening 12 is flattened by pressing).
The described methods of assembling the rotor have their respective drawbacks; for insert molding, the parts of the case 10 and the shaft 20 embedded in the connecting material 30 are small. During rotation, therefore, the shaft 20 or/and the connecting material 30 may separate from the case 10 due to insufficient rigidity of the case 10. Furthermore, connection via riveting has poor resistance to vibration. For fitting-and-riveting, therefore, the riveted part of the copper cover 40 may be broken during rotation so that the shaft 20 and the case 10 separate, particularly when the rotor is heavy or metal fatigue occurs.
In conclusion, the described methods of assembling the rotor fail to maintain the connection between the shaft and the case after long-term use. Thus, the application of the fan is limited. Frequent maintenance and replacement of parts of the rotor are unavoidable. The fans, produced by the described methods, fail to meet the demand of the manufacturing industry and the consumers for endurance of products. An improvement of the described rotors is necessary.